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Subject: Generator

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Theo Morris    Posted 08-28-2018 at 12:19:22 [URL] [DELETE]        [Reply] [No Email]  
  • Generator
  • What should I see out of a single post generator for voltage I put a brand new amp gauge and I see nothing on it as far as amp 1939 9N I have the round type cut out

    Tony C    Posted 08-30-2018 at 18:04:16 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Generator
  • Kevins' explanation is right on.

    WHy did you replace the ammeter? Was the battery running down causing you to think the generator/cutout was bad? Or were you worried because the needle didn't move very much? THey hardly move even at full throttle if the battery is fully charged. If you keep it hooked to a Battery Tender it may not move at all. Most of the Fords in good tune start in a revolution or two (sometimes less) in warm weather so there is little drain on the battery when starting. Drain to the coil is minimal and would be almost undetectable on the vehicle ammeter. On a quality tester reading in tenths, no problem.

    The ammeter ONLY reads amps. Your vehicle ammeter is connected inline (series) in the hot lead to the battery. Voltage can be tested across the battery terminals. 6.2V to a little over seven (over 7+ if the battery is older and a little sulphated.) depending on level of battery charge.

    The original and replacement gauges have wide needles and numbers close together, so interpolation (guessing) is necessary. Simply put the ammeter provides gross readings, You won't be able to tell if its charging the 1-2 amps to make up for the drain to the coil, especially if the commutator is a little worn and the brushes are bouncing a little.

    Easy check to see if it charging using the ammeter. Run the battery down a little by engaging the starter with the key and gas off. THen start it and watch the gauge. It should go up to around the 6-8 numbers and maybe wiggle a little depending on the condition of the generator with about half or better throttle and return to zero pretty quickly as the battery returns to full charge.

    You can also check for current at the battery posts with a test light, but that will only tell you that you are getting voltage.

    K.LaRue-VA    Posted 08-29-2018 at 07:25:11 [URL] [DELETE]        [Reply] [Email]  
  • Re: Generator
  • Measure voltage across the two battery terminals with engine off, and again with engine running. Anything between 6.5 and 7.0 volts is probably right, as long as the voltage is slightly higher with the tractor running. Gauge plus to battery plus, minus to minus.

    What you see on the amp gauge may be normal.
    If the battery is fully charged, and the tractor starts right up, amp gauge may not show much (if any) amps of charging current. The battery may have already been charged more than the tractor system is set-up to maintain. If you have headlights, flipping them on with the tractor running the amp gauge should show a momentary wiggle to negative, that immediately comes back to where it was. This shows the system reacted properly to the additional load. The ignition circuit draws so little current (none when the points are open) that you may not even see a wiggle on the amp gauge when the ignition is turned on or off.

    If you still think the generator is not charging, before doing anything else, polarize the generator.

    Tim Daley(MI)    Posted 08-29-2018 at 05:05:14 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Generator
  • All 1-Wire/3-Brush Ford Tractor generators, after s/n 9N-12500, using the round can cutout are the same. The chart shows p/n generator 9N-10000-C but the 2N-10000 generator is virtually the same. You are checking for voltage but the AMMETER registers amperes. There must be something in the wiring not right. Is the Ballast Resistor installed and wired correctly? How about the cutout wiring?

    9N/2N WIRING:

    Tim Daley(MI)

    Tom    Posted 08-29-2018 at 14:04:37 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Generator
  • Tim,
    Any chance you have the wiring diagram for before 9N12500? One of the early ones with the A genny and VR?

    Tim Daley(MI)    Posted 08-29-2018 at 16:16:45 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Generator
  • Tom-
    The wiring diagram for the early 9N-10000-A generator using the 9N-10505-A VOLTAGE REGULATOR is in the March, 1940 MPC right here in our MANUALS forum if you don't have a copy. You can download it for FREE to your PC then print it out from there or just print the diagram and the part number description page as needed. It is very important to know that the early 'A' generator is a "B" Circuit design, and polarizing it is different than the 'A' circuit designs. If you do it wrong, you will let all the smoke out of the VR. We also have a document in our HOW-TO's/ELECTRICAL with all the information on the early 9N and 2N generators -see LINK below. It also has the correct method of polarizing both A and B circuits. FWIW: The NAA Generator also used a 'B' Circuit Generator and VR. You can use the NAA VR, p/n FAG-10505-A, in place of the early 9N-A VR, just have to fab you own mounting bracket. Hope this helps you. If you need a new wiring harness, I know a place that makes them exact, with ignition "ON" lamp (you supply lamp) and the key switch on RH dash and the starter button on LH dash.

    Tim Daley(MI)

    HCooke    Posted 08-29-2018 at 16:15:16 [URL] [DELETE]        [Reply] [Email]  
  • Re: Generator
  • Right here on this site under the 'How Tos"

    Tom    Posted 09-07-2018 at 07:16:41 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Generator
  • Thanks guys- very helpful.

    JMOR    Posted 08-28-2018 at 13:14:41 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Generator
  • Connected to battery, you should see battery voltage rise from ~6v to around 7+v. If connected to nothing but meter, you may see as high as 17-18v, but don't do that for long or fields may be damaged.

    Theo Morris    Posted 08-28-2018 at 13:20:42 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Generator
  • I have an analog meter do I put the positive lead on the single post to ground to measure voltage since this is negative ground Iím not familiar with this type of system do I measure it from a single post a positive or negative

    JMOR    Posted 08-28-2018 at 13:42:31 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Generator
  • Terminal to ground (case). It might be either positive voltage or negative voltage depending on which way the generator was last polarized. If meter reads below zero, reverse leads.

    Theo Morris    Posted 09-02-2018 at 09:08:39 [URL] [DELETE]        [Reply] [Email]  
  • Re: Generator
  • I appreciate all the help you guys have given me . When i bought this tractor, wiring was out of it. I bought a new wiring kit off line. New gauges, ignition switch, pushbutton start, new ballast resistor. I turned the key and the tractor started. I didnít see the amp gauge move. I was wondering how much voltage should I see coming out of the generator. I took the wire off the generator. I wanted to see what it was putting out. There is an adjustment screw on the backside for moving it high or low. Also put in a new cut out round canister type. I double checked all my wiring connections and compared it to the wiring on this forum, seems to be the same. Also bought a new 6 V battery and two new cables. Put on two new front tires and working on the rears. I located two rims in Tennessee for my 9.5x32 tires that I bought for this 9N .The new rims are 8x32, the guy that I talked to was very knowledgeable on the tractor and the rims I needed . I bought the loop rims for $100 a rim.

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